Conventional automotive fuel delivery systems utilize an electric fuel pump mounted in the fuel tank as a motive force to deliver fuel from the fuel tank to the engine. Power is supplied to the fuel pump via electrical wires connected between a voltage source, such as an alternator or a vehicle battery, and the pump terminals. In order to reach the pump terminals, the electrical wires must pass through an opening in the fuel tank, which, unless properly sealed, potentially provides a path for fuel vapor leakage. Minimizing such vapor leakage is desirable due to increasingly stringent government regulations on automotive fuel vapor emissions.
Sealing of an opening has been accomplished in several ways, many involving a bushing or fitting adapted for placement in the opening with the wires passing therethrough, as shown in U.S. Pat. No. 3,308,316 (Pfahl). Although the wires are fitted as tightly as possible through the fitting, for example by insert molding, spaces or pores typically exists between them through which fuel vapor may leak.
Fuel vapor may also migrate along the wires, which are typically wrapped with insulation to maintain the electrical integrity of the connection. Some wire insulation swells when exposed to fuel causing cracking and breakage, thus revealing bare wire. Other types of insulation shrink when exposed to fuel, increasing the space between the wire and the fitting, thus increasing the size of the fuel vapor leakage path. When the insulation on wires passing through a fitting deteriorates due to shrinking or swelling, or when the wires are not sufficiently bound to the fitting, the pores between the wire and the fitting are widened providing a greater leak path for fuel vapor. In addition, the pull strength of the wires decreases as the bond between the fitting and the wires deteriorates, jeopardizing the electrical connection to the pump terminals.
Prior electrical fittings do not effectively compensate for these problems, in part by failing to use the proper wire, by failing to adequately seal the space between the wires and the fitting, and by failing to sufficiently bond the wires to the fitting. Other electrical connectors, such as that disclosed in U.S. Pat. No. 4,492,421 (Ito), require connection of two wires therein, potentially compromising the integrity of the connector through decreased pull strength and additional complexity. Unless properly sealed, such connectors potentially increase liquid or vapor migration due to capillary action at the broken cross-section of the wires.